Definition: Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Input: Context: Hypertension is a risk factor for atrial fibrillation. Activation of the renin-angiotensin-system seems to be involved in atrial enlargement, with release of atrial and brain natriuretic peptides. The aim of this study was to evaluate the relationship between ambulatory blood pressure and levels of natriuretic peptides, with left atrial size in normotensives with idiopathic atrial fibrillation.', 'This was a cross-sectional study in patients with idiopathic atrial fibrillation. The following measurements were recorded during the course of the study: office and 24-h ambulatory blood pressure, atrial and brain natriuretic peptides, plasma renin, aldosterone, and angiotensin-converting enzyme.', 'Forty-eight patients (mean age 55 [10] years; 70.6% male) were included in the study. Mean office sitting blood pressure values were 132.49 (14.9)/80.96 (9.2) mmHg. Mean 24-h ambulatory systolic and diastolic blood pressure values were 121.10 (8.3)/72.11 (6.8) mmHg (daytime, 126.8 [9.7]/77.58 [7.9] mmHg; nighttime, 114.56 [11.6]/68.6 [8.8] mmHg). A clear trend towards increased left atrial size with higher ambulatory blood pressure values was noted, which was statistically significant for nighttime values (r=0.34; P=.020 for systolic and r=0.51; p=.0001 for diastolic). A significant correlation between atrial natriuretic peptide and nighttime systolic (r=0.297; P=.047) and diastolic (r=0.312; P=.037) blood pressure was observed. Significant correlations were also observed between left atrial size and atrial natriuretic peptide levels (r=0.577; p<.0001) and brain natriuretic peptide levels (r=0.379; P=.012).
Answer: Nighttime blood pressure is associated with left atrial size and the release of natriuretic peptides in normotensive patients with idiopathic atrial fibrillation.

Is nighttime ambulatory blood pressure associated with atrial remodelling and neurohormonal activation in patients with idiopathic atrial fibrillation?